We are continuing our study of DNA replication and recombination in E. coli phage gamma. Our current approach makes use of a new technique of DNA isolation from infected cells whereby phage DNA free of bacterial DNA can be isolated in a very short period of time with a minimum of handling in concentrations suitable for observation by electron microscopy. We are making a catalog of structures as a function of time after infection using wild=type phage and various mutants blocked in different stages of replication and recombination.